Voice over Internet Protocol (VoIP) is being increasingly used by customers for local, long distance and international calls. The Session Initiation Protocol (SIP) is a well-known VoIP (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. These sessions include Internet telephone calls, multimedia distribution, and multimedia conferences.
With the popularity of VoIP and increasing deployments of VoIP interconnections, there is a strong need for internetworking various protocols, such as SIP, H.323, H.320, and H.324. Internetworking H.323 and SIP protocols has been achieved as specified in well-known standards documents (e.g. RFC4123) for basic connections. However, payload handling for internetworking these various VoIP protocols is not described in these standards documents. Payload handling for internetworking various VoIP protocols has become increasingly critical as more and more systems use dynamic payloads, such as new audio and video codecs.
Conventional SIP specifies the payload in the receiving direction in session description protocol (SDP). However, conventional H.323/H.320/H.324 protocols specify the payload in the transmitting direction. This payload handling mismatch causes interoperability problems when attempts are made to internetwork SIP and H.323/H.320/H.324 protocols. This is a common problem in all H.323/H.320/H.324 to SIP internetworking devices, such as time division multiplexed (TDM) gateways (H.324/H.320-SIP), session border controllers (SBC), Internet Protocol (IP) to IP gateways, Call Manager and Call Manager Express brand devices manufactured by Cisco Systems, Inc., Broadband Telephony Services (BTS), and the like.
Thus, an apparatus and method for handling dynamic payloads in a heterogeneous network are needed.